1. Field of the Invention
The present invention relates to a fitting device for fitting a fitting to a workpiece, which is held by a robot, to a workpiece to be fitted by force control.
2. Description of the Related Art
It is conventional to execute a fitting operation by using a controlling rule in which RCC (remote-center compliance) is imitated when a virtual compliance is composed. Japanese Examined Patent Publication No. 4-43744 discloses one method in which a rod-shaped fitting workpiece held by a robot hand is fitted into a fitting hole of a workpiece to be fitted.
According to the method disclosed in Japanese Examined Patent Publication No. 4-43744, a fitting workpiece is pressed against a workpiece to be fitted and a force and moment acting at the time are detected for each controlling period and control is effected so that the force and moment can be respectively a target value.
Further, Japanese Unexamined Patent Publication No. 4-25325 discloses a technique in which a disk hole is fitted to a spindle. According to Japanese Unexamined Patent Publication No. 4-25325, in the case where a position of the disk hole and that of the spindle greatly deviate from each other in a direction perpendicular to the fitting direction, in addition to the force given in the fitting direction, a force in the direction perpendicular to the fitting direction is generated so that a disk is moved in an oblique direction. Due to this operation, while a problem of the deviation between the two positions is being solved, the disk is fitted to the spindle.
In Japanese Examined Patent Publication No. 4-43744, consideration is given to a case in which a fitting workpiece is fitted to a workpiece to be fitted at two points. In this case, since forces acting at the two points contain components, the directions of which are opposite to each other, a resultant force of the forces acting at the two points is lower than the respective forces. Accordingly, the moment obtained from the resultant force also becomes lower. In the case where this moment is lower than the moment of disturbance caused by vibrations of a robot, it becomes difficult to change a posture of the fitting workpiece on the basis of this moment. Therefore, the time necessary for adjusting the posture of the fitting workpiece is greatly extended. Further, in the case where intensities of the forces acting at the two points are the same and directions are opposite to each other, the moment becomes zero. In this case, even when the long period of time is consumed, it is impossible to appropriately change the posture of the fitting workpiece.
Further, it is possible to consider that the technique disclosed in Japanese Unexamined Patent Publication No. 4-25325 is applied to a case in which a rod-shaped fitting workpiece is fitted into a fitting hole of a workpiece to be fitted. However, Japanese Unexamined Patent Publication No. 4-25325 does not disclose a technique in which a force different from the force in the fitting direction is generated in the direction such as a direction perpendicular to the fitting direction. Accordingly, there is a possibility that a force, the direction of which is not appropriate, is acted on the fitting workpiece and further there is a possibility that errors of the position and posture of the fitting workpiece are increased.
The present invention has been accomplished in light of the above circumstances. An object of the present invention is to provide a fitting device capable of appropriately adjusting a posture of a fitting workpiece in a short period of time in the case where clogging is caused between a fitting workpiece and a workpiece to be fitted.